... substratespecificity for its native substrate l-arginine, but alsotolerates l-homoarginine and l-canavanine (Fig. 3A,Table 1). These findings can be explained by the coor-dination of l-arginine in the active ... substrate. For example, in AsnO, a trans con-former is selected for the v1torsion angle of boundl-asparagine, whereas in VioC, a gauche(–) rotamer isobserved for l-arginine (Table 4). Owing to ... undergoing interactionsmainly with the C-terminal helical subdomain. Accordingly, VioC exertsbroadened substrate specificity by accepting the analogs l-homoarginineand l-canavanine for Cb-hydroxylation.AbbreviationsA-domain,...